One of two suicide bombers who hit the Brussels airport was the suspected bombmaker in the November attacks in Paris, suggesting that the attacks involved the same Islamic State cell, European officials have said.
Belgian, French, and European authorities told Belgian news media, AFP, and the Associated Press on March 23 that Najim Laachraoui's DNA was verified as that of one of the airport bombers on March 22 after samples were taken from remains found at the blast site.
The officials said they had been looking for Laachraoui since last week, suspecting he was an accomplice of top Paris attacks suspect Salah Abdeslam, who was arrested on March 18.
Laachraoui, 24, a Morrocan-born Belgian, is believed to have made the suicide vests used in the Paris attacks that killed 130 people, as his DNA was found on all of the vests as well as in a Brussels apartment where they were made.
Laachraoui also was believed to be a onetime recruiter for Islamic State.
His involvement suggests the Brussels and Paris attacks were carried out by "the same team," French senator Nathalie Goulet, the head of a parliamentary commission studying jihadi networks, told AP.
The revelation about Laachraoui came as Brussels residents struggled to regain a semblance of normal life and authorities identified two other suicide bombers that struck the city's airport and subway as brothers.
Federal prosecutor Frederic Van Leeuw said that airport bomber Ibrahim el-Bakraoui had left a will on a computer before the attacks, which killed at least 31 people.
Bakraoui's brother Khalid blew himself up in a subway car at Maalbeek station in central Brussels, Van Leeuw told a news conference.
"The [subway] suicide bomber was identified by his fingerprints. He is Khalid el-Bakraoui, Ibrahim's brother, born in Brussels on January 12, 1989, a Belgian national," Van Leeuw said. "The two dead terrorists had a heavy criminal record not linked to terrorism."
Laachraoui was one of two men shown pushing baggage carts with Ibrahim el-Bakraoui in widely publicized security-camera footage before the bombs went off. Investigators said the other is believed to have left the scene after depositing a bag stuffed with explosives at the airport. He has not been identified or apprehended.
Van Leeuw said his bag, which had the heaviest load of explosives, blew up after the arrival of bomb squads and caused no injuries.
He said a taxi driver who drove the three suspects to the airport led authorities to an apartment in the Schaerbeek district of Brussels where police found bomb-making equipment, including 15 kilograms of TATP explosives and a suitcase packed with nails and bolts.
Investigators discovered a computer containing Bakraoui's will in a garbage container close to the apartment, the prosecutor said. He said Bakraoui described himself as "not knowing what to do anymore, being searched for everywhere, no longer being safe."
Bakraoui also expressed fears of ending up in prison if he continued to "drag on," he said.
WATCH: Belgians, including a Muslim cleric and a local artist, give their thoughts, a day after suspected Islamic extremists killed at least 31 people in suicide bombings in Brussels. They were speaking at a community gathering to honor the dead in the center of Brussels.
The Brussels subway, the scene of carnage during the morning rush hour a day earlier, was partially running again on March 23. Security was tight, with soldiers checking passengers' bags at station entrances.
The district hosting European Union institutions reopened to vehicles, but Zaventem airport is scheduled to remain shut at least until March 25.
The terrorism alert level throughout Belgium remains at its maximum level following the attacks, which an Islamic State website said were conducted by its "soldiers of the caliphate."
Turkish President Recep Tayyip Erdogan said on March 23 that one of the Brussels attackers was caught in Turkey in June and deported to the Netherlands at his own request. He said Turkey also warned Belgium the man was a militant.
Speaking at a news conference, Erdogan said that "despite our warnings that this person was a foreign terrorist fighter, Belgium could not establish any links with terrorism."
Erdogan did not name the attacker, but an official in the Turkish president's office identified him as Ibrahim el-Bakraoui.
Van Leeuw said the attacks killed at least 31 people and wounded 270. Authorities said the death toll could rise because some of the victims of the subway bombing were blown to pieces.
Photos and videos posted on the Internet showed gruesome scenes of destruction at both sites.
Speaking to journalists on March 23, Belgian Prime Minister Charles Michel denounced what he called a "ruthless" attack on Europe's democratic values.
"We are more than ever determined to act and to defend the values that are close to our heart," he said. "We are being confronted with enemies of liberty and democracy who are hiding and attack cowardly. They attack anonymous victims with absolutely abominable brutality."
Belgium is observing three days of mourning for victims of the worst extremist attack ever in Brussels, which hosts both the EU and NATO headquarters.
As they tried to resume their daily lives, shocked residents still grappled with the horror of the attacks.
"This is going to make me rethink a lot of things," Michelle Sinn, a European Commission employee, told Reuters. She said the threat of terrorism "is clearly here" and it would now be difficult for Brussels residents to ignore it.
Linda Van Den Bossche called the attacks a "horrible" experience but said she was determined to continue enjoying life in her home city.
"Terrorism is coming close in a scary way," she said. "But still, Brussels is a beautiful city. We are not going to let our lives be dictated by the terrorists."
Speaking late on March 22, Belgian Interior Minister Jan Jambon said he shared these emotions but called on Belgians not to give in to fear.
"I think we have to give a place for these emotions," he said. "On the other hand, in our daily life we have to -- after some days of sadness -- we have to continue our life, because what [terrorists] want is to destabilize our society."
The attacks have sparked an international outpouring of sympathy, with leaders across the world extending their solidarity with Belgium.
U.S. President Barack Obama condemned the "outrageous attacks against innocent people," and EU leaders expressed anger over what Sweden's prime minister called an "attack against democratic Europe."
The attacks also prompted calls for tougher counterterrorism measures.
French Prime Minister Manuel Valls urged the EU parliament to authorize a passenger name record that would cover the whole of Europe.
"There is an urgent need to strengthen the external borders of the European Union," he told French radio.
He said Islamic State had "stolen a large number of passports in Syria" and that heightened vigilance was required to prevent people from crossing into Europe with false passports.
Belgium has been in the spotlight since militants living there helped carry out the coordinated attacks in Paris on November 13.
The Brussels blasts came four days after Salah Abdeslam, the chief surviving suspect in the Paris attacks, was captured following a shoot-out in Brussels. Belgian security forces had been on alert for any reprisal action.
Media reports said one of the brothers suspected of carrying out the bombings used a false name to rent an apartment in Brussels where police killed a gunman last week.
During that operation, police found fingerprints belonging to Abdeslam. He was arrested last week in Brussels and is awaiting trial. The first hearings have reportedly been postponed for a day to March 25 due to security concerns in the Belgian capital.